JavaFX鼠標拖動窗體代碼

JavaFX學習，通過鼠標拖動窗體代碼

package ch04;

/**
  @package      ch04 
  @file         DraggingStage.java
  @date         2020/12/31
  @author       qiaowei
  @version      1.0
  @brief        
 */

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class DraggingStage extends Application {

    public static void main(String[] args) {
        Application.launch(DraggingStage.class, args);
    }

    @Override
    public void start(Stage primaryStage) {
        // Store the stage reference in the instance variable to
        // use it in the mouse pressed event handler later.
        this.stage = primaryStage;
        
        Label msgLabel = new Label("Press the mouse button and drag.");
        
        Button closeButton = new Button("Close");
//        closeButton.setOnAction(e -> stage.close());
        closeButton.setOnAction(e -> primaryStage.close());
        
        VBox root = new VBox();
        root.getChildren().addAll(msgLabel, closeButton);
        
        Scene scene = new Scene(root, 300, 200);
        // Set lambda of mouse pressed and dragged even handlers for the scene
        scene.setOnMousePressed((ev) -> handleMousePressed(ev));
//        scene.setOnMousePressed(this::handleMousePressed(e));
        scene.setOnMouseDragged(e -> handleMouseDragged(e));
        
        stage.setScene(scene);
        stage.setTitle("Moving a Stage");
        // Setup the style of stage
        stage.initStyle(StageStyle.UNDECORATED);
        stage.show();
    }

    /********************************************************************************************************
     @class      DraggingStage
     @date       2021/6/21
     @author     qiaowei
     @version    1.0
     @brief      The press mouse event
     @param      e mouse event
     ********************************************************************************************************/
    protected void handleMousePressed(MouseEvent e) {
        // Store the mouse x and y coordinates with respect to the
        // stage in the reference variables to use them in the drag event
        // 點擊鼠標時，獲取鼠標在窗體上點擊時相對應窗體左上角的偏移
        this.dragOffsetX = e.getScreenX() - stage.getX();
        this.dragOffsetY = e.getScreenY() - stage.getY();
    }
    
    protected void handleMouseDragged(MouseEvent e) {
        // Move the stage by the drag amount
        // 拖動鼠標後，獲取鼠標相對應顯示器座標減去鼠標相對窗體的座標，並將其設置爲窗體在顯示器上的座標
        stage.setX(e.getScreenX() - this.dragOffsetX);
        stage.setY(e.getScreenY() - this.dragOffsetY);
    }

    /********************************************************************************************************
     @date      2021/6/21
     @author    qiaowei
     @brief     Main window
     ********************************************************************************************************/
    private Stage stage;

    /********************************************************************************************************
     @date      2021/6/21
     @author    qiaowei
     @brief     The x coordinate while pressing mouse
     ********************************************************************************************************/
    private double dragOffsetX;

    /********************************************************************************************************
     @date      2021/6/21
     @author    qiaowei
     @brief     The y coordinate while pressing mouse
     ********************************************************************************************************/
    private double dragOffsetY;
}